[jira] [Created] (SPARK-57809) Support nanosecond-precision timestamps in collect_list/listagg ordering safety

["Max Gekk (Jira)" <ji...@apache.org>]

Max Gekk created SPARK-57809:
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             Summary: Support nanosecond-precision timestamps in collect_list/listagg ordering safety
                 Key: SPARK-57809
                 URL: https://issues.apache.org/jira/browse/SPARK-57809
             Project: Spark
          Issue Type: Sub-task
          Components: SQL
    Affects Versions: 4.3.0
            Reporter: Max Gekk


This sub-task is part of the umbrella SPARK-56822 (timestamps with nanosecond precision).

h2. Problem
{{collect.scala}} {{isCastEqualityPreserving}} (~L750-762) marks {{TimestampNTZType}} as cast-equality-preserving and {{TimestampType}} (LTZ, DST) as unsafe, but has no arm for {{TimestampNTZNanosType}} / {{TimestampLTZNanosType}}, so both fall to {{case _ => false}}. NTZ nanos should be treated like NTZ micro (safe); LTZ nanos like LTZ micro.

h2. Goal
Add nanosecond arms so the ORDER BY-cast optimization applies to NTZ nanos and correctly excludes LTZ nanos, matching the microsecond behavior.

h2. Scope
Extend {{isCastEqualityPreserving}} (and any sibling checks) for {{TimestampNTZNanosType}} and {{TimestampLTZNanosType}}.

h2. Acceptance criteria
* Ordered {{collect_list}} / {{listagg}} over NTZ nanos uses the safe path; LTZ nanos keeps the same DST caveat as micro LTZ.

h2. Testing
{{collect.scala}}-related suites; targeted unit test.

h2. Dependencies
None - independent (builds on the resolved widening/cast infrastructure).




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